1. Field of the Invention
The present invention relates to routing packets through a network and, more particularly, to routing packets using encoded signals.
2. Background Information
As technology advances, it has become increasingly common to couple separate nodes together so that the combination realizes greater computational power, such as for a cluster. In this context, a cluster refers to a network of nodes coupled in a known or predetermined configuration. In this context, the term node refers to a server, workstation, personal computer (PC), network connected input-output device, or network connected computing device. As clusters increase in size and power, by coupling additional nodes together, one issue relates to routing packets of information in the form of electronic or electrical signals between the nodes. Typically, the routing is performed by one or more switches that are employed to couple the plurality of nodes together. In a typical network, each node is coupled to a network interface component (NIC) and these network interface components are coupled to a switch or a plurality of switches. Typically, the network interface components include an encoder that encodes and serializes the signals for transmission across a link to a switch.
An emerging trend in data transfer between two system components is the use of serial links. This method has a number of advantages including cost effectiveness; however, to send these signals serially it is desirable to encode the bit stream so that at least a selected number and a selected frequency of bit transitions occur in the bit stream. These transitions are desirable so that a clock signal may be derived from the bit stream, such as by using a phase locked loop or delay locked loop, for example. A clock signal is employed to latch the data at the receiving component. One common method of encoding is described in “A DC-Balanced, Partitioned-Block, 8 B/10 B Transmission Code” by A. X. Widmer and P. A. Franaszek, published in IBM.J RES. DEVELOP., Volume 27, Number 5, September 1983, herein incorporated by reference. One disadvantage of this encoding approach is that at the receiving end of each link, the binary digital signals are deserialized and decoded. This introduces additional hardware and additional complexity into the system. A need therefore exists for addressing this problem.